The effect of seed soaking and foliar sprays of 0.1, 0.01 and 0.001% potassium naphthenate (K-Nap) solutions on rice O. sativa L., cv. IRRI-6 was investigated. Soaking of seeds in each of the solutions significantly (P < 0.05) increased the number or productive tillers per pot but it did not materially affect the grain weight, K-NaP spray of 0.001%, in addition to seed soaking, further increased the straw weight but grain weight and number of grains per fertile tiller decreased.